壳聚糖基大分子引发剂引发寡聚乙二醇甲基丙烯酸酯单电子转移-活性自由基聚合动力学

Kinetics of the SET-LRP of Oligo(ethylene glycol) Methacrylate Initiated with Chitosan Based Macroinitiator

摘要: 以O-溴化壳聚糖（CS-Br）为大分子引发剂，Cu（I）Br为催化剂，通过单电子转移活性自由基聚合（SET-LRP），合成了壳聚糖 O-寡聚乙二醇甲基丙烯酸酯（CS-O-POEGMA），用原位核磁研究了寡聚乙二醇甲基丙烯酸酯（OEGMA）在不同聚合条件下的聚合反应动力学。结果表明：随着介质pH的降低，配体发生质子化，导致聚合速率下降；在缓冲溶液中，随着CS-Br浓度的升高，反应过程中体系发生凝胶化；pH=5.0的介质中，CS-Br中溴代异丁酸的取代度对反应动力学基本无影响，表明该介质中壳聚糖分子链较舒展，反应可控性最佳。

Abstract: Chitosan O-poly(oligo(ethylene glycol) methacrylate) (CS-O POEGMA) was synthesized through single electron transfer living radical polymerization (SET-LRP) of OEGMA, using O brominated chitosan (CS-Br) as an initiator and Cu (I)Br as the catalyst. The polymerization kinetics under different conditions was studied using in situ 1H NMR. Results showed that with the decreasing of medium pH, the polymerization rate declined. When CS-Br concentration was raised to a certain extent, gelation took place during polymerization. The degree of substitution of bromobutyrate groups in CS-Br had little effect on the polymerization kinetics in pH 5.0 buffer solution, suggesting the conformation of chitosan backbone was in an extended state and the controllability of the polymerization was the best.